We’ve got a deep low (988 hPa) semi-stationary in the Central Tasman with strong high pressure support south-west of Tasmania and a broad coverage of strong winds to low end gales through the southern Tasman.
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A secondary front pushing into the Tasman coalesces with a deepening low near New Zealand and the system then retrogrades back into the Tasman over an already active sea state delivering powerful S/SE swell before taking up residency in the Central Tasman for a few days next week with a slow, slow easing in big swells expected.
Following that a secondary front coalesces with the primary front to form a complex Tasman low which is expected to occupy the Tasman for a meaningful period of time, even retrograding back towards the East Coast over the weekend.
The main synoptic activity this week will be related to an amplifying node of the Long Wave Trough which is expected to slide through the Tasman Sea before parking itself across New Zealand longitudes later in the week. We’ll see a prolonged round of large to very large swell as a result.
We’ve got a complex weekend of small waves. And then a very active period from the south.
Troughy remnants remain off the North Coast and South Coast interior and these troughs are expected to deepen and reform into another surface low through Fri into the weekend with another round of E/NE infeed swell and S swell although much more subdued than last weekends swell.
A trough line connected to the low remains angled SW/NE in the Tasman with a N-N/NE infeed along the trough line. With the movement of the low into the coast, winds on the southern flank are now out of the swell window so we’ll be relying on the NE infeed into the trough and potential small lows forming in the trough line for swells in the short term once the current S/SE swell fades out.
A lingering coastal trough is expected to slowly evolve into a closed circulation through Saturday.
Under current modelling, by first light Sat morning a trough of low pressure will be deepening due east of the Illawarra.
A pair of weak cold fronts are expected to pass over Tasmania in the short term, generating small S swells which will overlap with the last pulses coming from the polar low now SE of New Zealand. A dynamic, troughy pattern looks set to unfold over the weekend.